Any data which is delivered over a network is vulnerable to having errors introduced into the data. This problem is particularly prevalent in networks with multiple components and especially where no single entity controls all of the network components between the sender and receiver of the data.
For example, networks which deliver interactive television have many components which are likely to be geographically remote from one another and are frequently under the control of a multiple entities. An example of this kind of network is one where a content provider (e.g., Home Box Office® (HBO®)) has provided content (e.g., a movie) to an interactive television service provider for delivery to subscribers using a Video-On-Demand (VOD) system where the subscriber selects a movie using a Graphical User Interface (GUI).
FIG. 1 shows an example of a network implementing a VOD service. The content provider prepares and delivers a Movies-On-Demand (MOD) data package 100 to an interactive television service provider. The MOD package 100 contains the audio and video for the movie as well as other data that is used to provide at least part of the GUI display that the subscriber views when ordering a movie.
The interactive television service provider loads the MOD package into an Asset Management/Business Management system such as the MediaPath™ system by N2Broadband, Inc of Duluth, Ga. The Asset Management Server (AMS) 110 maintains a catalogue of the content (e.g., movies in this case) that is available on the VOD service. The Business Management Server (BMS) 120 handles the business and billing aspects of the VOD service by, for example, applying business rules to perform subscription checking and ensuring that subscribers are properly billed for their use of the service. The audio and video that are to be delivered to the subscriber when a movie is ordered are then stored in one or more VOD servers 140 (e.g., a MediaCluster™ by SeaChange International of Maynard, Mass.) that may be located remotely from the AMS 110 and BMS 120 so as to serve geographically diverse subscribers. The interaction over the network between the subscribers and the VOD service is managed by a Digital Storage Management-Command and Control (DSM-CC) 130 data carousel such as the Digital Network Control System (DNCS) by Scientific-Atlanta, Inc. of Lawrenceville, Ga.
Each subscriber has a Set Top Box (STB) 160 which connects to the subscriber's television 170 and connects to the DSM-CC 130, VOD server 140, AMS 110, and BMS 120 via the “cable plant” 150 of the subscriber's cable provider (which may or may not be the same as the interactive television service provider). This cable plant consists primarily of the various hardware and software components (e.g., network switches, etc) required to provide connectivity between the STB 160 and the VOD service components. The STB 160 may be, for example, a Scientific-Atlanta Explorer 3000® running PowerTV® operating system software and the Prasara user interface application.
When a subscriber accesses the VOD service to order a movie, the subscriber is first presented with the GUI, including information from the MOD package 100 as provided by the AMS 110. The subscriber may then request to order the movie. The request to order the movie is routed through the DSM-CC 130 to the BMS 120 to determine if the subscriber is authorized to order the movie and ensuring that billing for the service is properly handled. Once the BMS 120 authorizes the movie order request, a VOD server 140 streams the movie audio and video to the STB 160 which decodes the data and plays the movie on the subscriber's TV 170.
There are numerous opportunities at a variety of places in the network for errors to be introduced into the GUI that is displayed to the user, and even the movie data itself. For example, the interactive television service provider may manually load the MOD package 100 into the AMS 120, possibly editing portions of the GUI data in the process, and errors may be introduced into the data. In another example, errors may be introduced simply through corrupted transmission from one component in the network to another especially when data elements from the same data package are stored on different components in the system. Errors may also be introduced due to inconsistencies between the software in different models of STBs.
These errors may be as trivial as a misspelling in the title of the movie or the artwork to be displayed on the GUI may be corrupted. These errors may also be much more serious such as the complete corruption of the movie's audio or video or the mismatching of different data elements such as misclassification of adults-only material as children's content.
Present quality assurance techniques rely on direct inspection by a human, which is not practical, or on dedicated testing systems such as the TestQuest Pro™ system by TestQuest, Inc. of Minneapolis, Minn., which are computationally intensive and cannot simply and easily address errors that are introduced during transmission to the subscriber.